Hi All,
I am sure that my questions is a very generic one , probably a pure java
problem. However i have been trying to find a way to identify whether
three coordinates are collinear using the same logic of finding it doesnt
seem to work on examples which take 'Points' as inputs.
Two approaches can be
1. Find the area of the triangle forming the three coordinates/points . If
they are on the same line; the value of area must be zero.
2. Split the line joining these coordinates into two and find the
individual slopes for the same. If they are on the same line, the slopes
will be same.
The following is the method i am trying.
*
private* *boolean* collinearCheck( Coordinate endPointOne , Coordinate
intersection,Coordinate endPointTwo ){
*boolean* isCollenear = *false*;
//Area of triangle approach
*double* area = (Math.*round*(endPointOne.x )* (Math.*round*(intersection.y)
- Math.*round*(endPointTwo.y)) + Math.*round*(intersection.x )* (Math.*round
*(endPointTwo.y) - Math.*round*(endPointOne.y)) +
Math.*round*(endPointTwo.x) * (Math.*round*(endPointOne.y) - Math.*round*
(intersection.y)));
if((endPointOne.x * (intersection.y - endPointTwo.y) + intersection.x *
(endPointTwo.y - endPointOne.y) +
endPointTwo.x * (endPointOne.y - intersection.y))<= 0)
*if*(Math.*round*(area) <= 0)
{
isCollenear = *true*;
}
// Slope Approach
double numeratorOne = Math.round(intersection.y) -
Math.round(endPointOne.y);
double denominatorOne = Math.round(intersection.x) -
Math.round(endPointOne.x);
double numeratorTwo = Math.round(endPointTwo.y) -
Math.round(intersection.y);
double denominatorTwo = Math.round(endPointTwo.x) -
Math.round(intersection.x);
double result1 = Math.round(numeratorOne/denominatorOne);
double result2 = Math.round(numeratorTwo/denominatorTwo);
if(result1== 0 && result2==0){
isCollenear = true;
}
*return* isCollenear;
}
In both these cases while using coordinates as inputs ; even for simingly
collinear situations i end up getting values like 4 etc for the area. And
for situations that are clearly non collinear; i end up getting the same
value for slope.
Is there a way I can obtain the clear notifier of collinearity using any
udig construct? Is my approach correct?
The sample value for coordinates i pass to the method are
Coordinate endPointOne = -26.666666666666686, 32.38095238095238 .... etc
Looking forward for your inputs.
Thanks & Regards
VS
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